1. Field of the Invention
The present invention relates generally to disease simulation systems, and in particular to a system and method for simulating a disease control parameter and for predicting the effect of patient self-care actions on the disease control parameter.
2. Description of Prior Art
Managing a chronic disease or ongoing health condition requires the monitoring and controlling of a physical or mental parameter of the disease. Examples of these disease control parameters include blood glucose in diabetes, respiratory flow in asthma, blood pressure in hypertension, cholesterol in cardiovascular disease, weight in eating disorders, T-cell or viral count in HIV, and frequency or timing of episodes in mental health disorders. Because of the continuous nature of these diseases, their corresponding control parameters must be monitored and controlled on a regular basis by the patients themselves outside of a medical clinic.
Typically, the patients monitor and control these parameters in clinician assisted self-care or outpatient treatment programs. In these treatment programs, patients are responsible for performing self-care actions which impact the control parameter. Patients are also responsible for measuring the control parameter to determine the success of the self-care actions and the need for further adjustments. The successful implementation of such a treatment program requires a high degree of motivation, training, and understanding on the part of the patients to select and perform the appropriate self-care actions.
One method of training patients involves demonstrating the effect of various self-care actions on the disease control parameter through computerized simulations. Several computer simulation programs have been developed specifically for diabetes patients. Examples of such simulation programs include BG Pilot.TM. commercially available from Raya Systems, Inc. of 2570 El Camino Real, Suite 520, Mountain View, Calif. 94040 and AIDA freely available on the World Wide Web at the Diabetes UK website http://www.pcug.co.uk/diabetes/aida.htm.
Both BG Pilot.TM. and AIDA use mathematical compartmental models of metabolism to attempt to mimic various processes of a patient's physiology. For example, insulin absorption through a patient's fatty tissue into the patient's blood is represented as a flow through several compartments with each compartment having a different flow constant. Food absorption from mouth to stomach and gut is modeled in a similar manner. Each mathematical compartmental model uses partial differential equations and calculus to simulate a physiological process.
This compartmental modeling approach to disease simulation has several disadvantages. First, understanding the compartmental models requires advanced mathematical knowledge of partial differential equations and calculus which is far beyond the comprehension level of a typical patient. Consequently, each model is an unfathomable "black box" to the patient who must nevertheless trust the model and rely upon it to learn critical health issues.
A second disadvantage of the compartmental modeling approach is that a new model is needed for each new disease to be simulated. Many diseases involve physiological processes for which accurate models have not been developed. Consequently, the mathematical modeling approach used in BG Pilot.TM. and AIDA is not sufficiently general to extend simulations to diseases other than diabetes.
A further disadvantage of the modeling approach used in BG Pilot.TM. and AIDA is that the mathematical models are not easily customized to an individual patient. As a result, BG Pilot.TM. and AIDA are limited to simulating the effect of changes in insulin and diet on the blood glucose profile of a typical patient. Neither of these simulation programs may be customized to predict the effect of changes in insulin and diet on the blood glucose profile of an individual patient.